I. Technical Field
The present invention relates generally to electrically-powered devices, and more particularly to a circuit for switching between multiple power sources.
II. Background Art
Many modern devices are electrically powered. Oftentimes, such power is supplied by one or more portable power sources, such as a battery. As used herein, the term “battery” refers generally to any cell that may store energy and furnish the stored energy as an electrical current. For example, batteries may be electrostatic or electrochemical in nature.
Certain devices may use multiple batteries connected in parallel. Often this is done in order to extend the operation of the device; by providing multiple batteries, the device may draw power from one battery individually or both batteries simultaneously. Presuming the device's operation requires a fixed power, the overall operating life of the device may be extended by using multiple batteries.
As electronic devices have become more and more popular, compact, and advanced, they have come to rely heavily on batteries for power. It is not always practicable or useful to power electronic devices from a fixed or corded power supply. For example, wireless computer peripherals such as keyboards and mice that communicate with a computer by infrared or radio frequency, such as Bluetooth, have no hardwired connection through which power may be supplied. Accordingly, these devices generally employ batteries to operate.
Many other electronic devices, such as remote controls, calculators, cameras, watches, toys, games, and so forth likewise employ multiple batteries for operation.
An ongoing trend (particularly with respect to consumer electronics) is the concept of miniaturization. Electronic devices have become smaller and smaller; many modern electronic devices may perform the same functions as a device multiple times their size could only a few years ago. However, as electronics continue to shrink in size, space for circuitry and electronic components within devices becomes an issue. A premium is thus often placed on fitting the same functionality for a given circuit or component within a small footprint.
Given these constraints in battery-powered devices, certain issues may emerge. For example, although many electronic devices employ some form of battery-switching device to ensure power is drawn from the one battery having the highest voltage in an array of batteries, such switching devices typically require one boost converter for each battery (or at least multiple boost converters). Where space and/or cost is at a premium, it may be undesirable to use multiple boost converters in a single switching circuit.
Likewise, the use of multiple boost converters in a single battery-switching circuit requires power and voltage to drive each of the boost converters. This adds to the overall power consumption of the circuit, which in turn depletes the batteries faster and shortens the operational life between battery changes of the associated electronic device.
Accordingly, there is a need in the art for an improved battery-switching circuit.